Viabilidade da recuperação de longarinas automotivas: uma análise comparativa de resistência mecânica

Abstract

This work analyzes the technical feasibility of recovering automotive structural components, using SAE 1008 Carbon Steel tubular profiles as analogs. The motivation arises from the author's professional experience in vehicle inspections, which revealed the frequent use of structural repairs performed without proper technical criteria. To isolate the repair variables, an experimental comparison was conducted by subjecting specimens to axial compression tests in their original state (n=5) and, subsequently, after a standardized repair process by section replacement and MIG/MAG welding (n=4). The quantitative results revealed an average loss of maximum strength of 28.32% in the recovered specimens (140.1 kN) compared to the original ones (195.4 kN). The qualitative analysis demonstrated a critical change in the failure mode: while the original parts failed at random points, the repaired parts consistently failed in the Heat-Affected Zone (HAZ), adjacent to the weld bead. It is concluded that the welding repair, under the studied conditions, introduces a predictable weak point that significantly compromises structural integrity, questioning the feasibility of repairs that do not include post-weld heat treatment.